Oxygen defects-induced charge transfer in Bi7O9I3 for enhancing oxygen activation and visible-light degradation of BPA

Two-dimensional (2D) bismuth-based semiconductors have aroused intensive concern owing to their prominent photocatalytic activity for organic pollutants removal . In this work, a facile strategy for introducing oxygen vacancy in Bi-based oxyiodides (Bi x O y I z ) sheet-like architectures to activate molecular oxygen was proposed. The structure, photoelectric properties and visible light (λ > 420 nm) induced photocatalytic activities of these samples for decomposition of bisphenol A (BPA) were systematically characterized and evaluated. The as-prepared Bi 7 O 9 I 3 with a feeding Bi/I molar ratio of 1:1 exhibited the best photocatalytic activity comparable to those of similarly synthesized Bi 7 O 9 I 3 with other molar ratios and BiOIO 3 catalysts. The optimal Bi 7 O 9 I 3 achieved excellent photocatalytic activity with 99.6 % degradation efficiency of BPA within 20 min and superior structural stability with 95.1 % degradation retention over 5 cycling tests. In addition, the resulting Bi 7 O 9 I 3 sample displayed a high mineralization efficiency of BPA. Importantly, the plenty of oxygen vacancies (V o s) exsiting in Bi 7 O 9 I 3 played the dominant role in both accelerating electron transfer and activating molecular oxygen to facilitate the generation of superoxide radical (O 2 ·- ) and singlet oxygen ( 1 O 2 ), thereby proceeding oxidative degradation of BPA molecules during photoreactions. The efforts and attempts are also extendable to synthesis other 2D photocatalysts, providing potential for effective charge-carrier separation and molecular oxygen activation.